Russian Prime Minister Dmitry Medvedev says it is vital that a conflict between Azerbaijan and Armenia-backed separatists over the breakaway territory of Nagorno-Karabakh does not slide into a "hot phase."

On a visit to Armenia on April 7, Medvedev said Russia was ready to continue to act as an intermediary in resolving the conflict and hoped a cease-fire agreement would hold.

Dozens of people were killed in Nagorno Karabakh in fighting that erupted on April 2 between Azerbaijan's military and Armenian-backed separatists.

It was the worst fighting since a 1994 cease-fire that stopped the conflict but did not resolve the underlying dispute.

A tense calm has held since a cease-fire was agreed on April 5.

On April 7, each side alleged the other had violated the truce in skirmishes overnight. Each said one of their servicemen was killed.

Those incidents aside, the cease-fire was broadly holding, reports said.

On a visit to Azerbaijan's capital, Baku, Russian Foreign Minister Sergei Lavrov emphasized Moscow's special role as mediator.

"Beyond all doubt, we are interested -- maybe more than the other foreign partners of these two countries -- in this conflict being settled as soon as possible," Lavrov said after meeting his Azerbaijani counterpart on April 7.